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14.2.7 声明的安全性
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14.2.7 声明的安全性
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2006-10-13 14:41:00
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<div style='float:left;width:49%'>·<a href='100165427.htm'>14.2.4 拒绝权限</a></div><div style='float:right;width:49%'>·<a href='100165428.htm'>14.2.5 断言权限</a></div><div style='float:left;width:49%'>·<a href='100165429.htm'>14.2.6 创建代码访问权限</a></div><div style='float:right;width:49%'>·<a href='100165431.htm'>14.3 基于角色的安全性</a></div><div style='float:left;width:49%'>·<a href='100165432.htm'>14.3.1 Principal</a></div><div style='float:right;width:49%'>·<a href='100165433.htm'>14.3.2 Windows Principal</a></div></div>
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<div id="text"> <link href="css.css" rel="stylesheet" type="text/css" /><h3 style="MARGIN-TOP: 8.15pt; MARGIN-LEFT: 0cm; MARGIN-RIGHT: 0cm; FTEL: 8.15pt"><a ftel="_Toc507815610"><span lang="EN-US">14.2.7 </span></a><span style="FONT-FAMILY: 黑体">声明的安全</span><span style="FONT-FAMILY: 黑体">性</span></h3>
<p class="MsoNormal"><span style="FONT-FAMILY: 宋体">通过调用</span><span lang="EN-US">.NET Framework</span><span style="FONT-FAMILY: 宋体">中的类，可以拒绝、请求和断言权限，除此之外，还可以使用属性，声明指定权限需求。</span></p>
<p class="MsoNormal"><span style="FONT-FAMILY: 宋体">使用声明安全性的最大好处是通过反射可以访问设置信息。对于系统管理员而言，这也是非常有益处的，因为他们需要经常查看应用程序的安全需求。</span></p>
<p class="MsoNormal"><span style="FONT-FAMILY: 宋体">例如，可以指定一个方法，它必须具有从</span><span lang="EN-US">C:\</span><span style="FONT-FAMILY: 宋体">目录下读取数据的权限才能执行，其代码如下所示：</span></p>
<p class="2" style="MARGIN-TOP: 8.15pt; MARGIN-LEFT: 21.45pt; MARGIN-RIGHT: 0cm; FTEL: 18.45pt"><span lang="EN-US">using System;</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; FTEL: 18.45pt"><span lang="EN-US">using System.Security.Permissions;</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; FTEL: 18.45pt"><span lang="EN-US">namespace Wrox.ProCSharp.Security</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; FTEL: 18.45pt"><span lang="EN-US">{</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; FTEL: 18.45pt"><span lang="EN-US"> class SecurityApp6</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; FTEL: 18.45pt"><span lang="EN-US"> {</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; FTEL: 18.45pt"><span lang="EN-US"> static void Main(string[] args)</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; FTEL: 18.45pt"><span lang="EN-US"> {</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; FTEL: 18.45pt"><span lang="EN-US"> MyClass.Method();</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; FTEL: 18.45pt"><span lang="EN-US"> }</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; FTEL: 18.45pt"><span lang="EN-US"> }</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; FTEL: 18.45pt"><span lang="EN-US"> </span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; FTEL: 18.45pt"><span lang="EN-US"> [FileIOPermission(SecurityAction.Assert, Read="C:\\")]</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; FTEL: 18.45pt"><span lang="EN-US"> class MyClass</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; FTEL: 18.45pt"><span lang="EN-US"> {</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; FTEL: 18.45pt"><span lang="EN-US"> public static void Method()</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; FTEL: 18.45pt"><span lang="EN-US"> { </span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; FTEL: 18.45pt"><span lang="EN-US"> </span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; FTEL: 18.45pt"><span lang="EN-US"> // implementation goes here</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; FTEL: 18.45pt"><span lang="EN-US"> </span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; FTEL: 18.45pt"><span lang="EN-US"> }</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; FTEL: 18.45pt"><span lang="EN-US"> }</span></p>
<p class="2" style="MARGIN-TOP: 0cm; MARGIN-LEFT: 21.45pt; MARGIN-RIGHT: 0cm; FTEL: 18.45pt"><span lang="EN-US">}</span></p>
<p class="MsoNormal"><span style="FONT-FAMILY: 宋体">注意，如果使用属性断言或请求权限，就不能捕捉到操作失败时引发的异常，因为在</span><span lang="EN-US">try-catch-finally</span><span style="FONT-FAMILY: 宋体">子句中没有放置命令式代码。</span></p></div>
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<h1 id="divCurrentNode2" style="color: #b83507; width: 100%; text-align: left; font-size: 12px; padding-left: 2px">当前章节:<a href='100165430.htm'><font color='red'>14.2.7 声明的安全性</font></a></h1>
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<div style='float:left;width:49%'>·<a href='100165427.htm'>14.2.4 拒绝权限</a></div><div style='float:right;width:49%'>·<a href='100165428.htm'>14.2.5 断言权限</a></div><div style='float:left;width:49%'>·<a href='100165429.htm'>14.2.6 创建代码访问权限</a></div><div style='float:right;width:49%'>·<a href='100165431.htm'>14.3 基于角色的安全性</a></div><div style='float:left;width:49%'>·<a href='100165432.htm'>14.3.1 Principal</a></div><div style='float:right;width:49%'>·<a href='100165433.htm'>14.3.2 Windows Principal</a></div></div>
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